Oh boy she's a tough one. Sounds as persistent as my daughter!
Vent away!
So after telling my sil that we had plans with other people she called 4 more times to see if we wanted to meet up at he parade!!!!!! I was ready to scream- I stopped answering the phone. I know this is her adhd causing her to do this- she either can't remember what I told her or she thinks if she pesters me enough I'll invite them along or she doesn't even think. Now she's called me again to invite me to some direct marketing party she's having that I have told her once a week for the past month that I will not be able to attend.
Is there a polite way to tell someone that they need to get treatment?
We do try to meet up places- like the park- but still run into the problem of them not watching their kids. And 9 times out of 10 they think of some excuse to try to invite themselves over anyway.
Thanks for letting me vent again. 
I'm sorry you have such difficult relatives. It puts you in such an awkward position.
You asked how to let SIL know that she needs treatment. I don't know your relationship with her, but could you point out some of the things you've observed, say that you're concerned about her, and continue that you know from your own kids how much treatment can help these sorts of issues? It would be hard to have it come across in a way that doesn't sound critical, judgmental, or condescending, but maybe she would be open to hearing it? If that approach wouldn't work, could you talk about the behaviors without pointing out that she's doing them? Maybe your kids do some of the stuff she has an issue with, and you could talk about their behavior and say that you know it's linked to ADHD, that the meds help w/ it, etc. Maybe indirectly SIL would get the idea that treatment might help her, or if she's not one to pick up on such subtleties, maybe you then could point out that she does the same stuff. but it might not be as threatening to her because you were just talking about the same stuff in a caring way relating it to yourkids? No clue if any of this helps! It's hard to comment without knowing how open she is to feedback.
I'm kind of stuck with a family "situation" and feeling really horrible for feeling the way I do about it.
My brother, his wife, and his two stepkids (7 and 6) all have adhd. It remains to be seen about their 1.5 yr. old, but chances are. . . So the problem is that they are really hard to communicate with- everything you tell them gets mixed up and everything involves a lot of drama. None of them are getting effective treatment. My SIL told me that the boy needs twice as much adderall as he's being prescibed (I would have to agree) and it's working ok for the girl, but could be better. The ped that they're seeing won't up give the boy a higher dose because "he acts fine in the office". This has been going on for almost 6 months and she hasn't done anything about it- there are 3 other docs in the practice that they could see, not to mention numerous other docotrs in the area.
My brother is finally seeing a doctor and said he's doing a little better on zoloft (versus vodka and illicit controlled substances) and SIL thinks she is fine (she was dx'ed and medicated as a child, but quit meds when she outgrew the hyperness).
I just feel horrible because I've been blowing them off every time they try to make plans with us to do something. The finally straw was when she called to find out what we were doing tomorrow (July 4th). I told her we had plans with our neighbors (which we tentatively do), but if it wasn't such a hassle, not to mention downright unpleasant being around them, I could have invited them to come as well. Last year my brother showed up at the 4th of July parade drunk (with vodka in his water bottle) and ranted the whole time about the freemasons. Now, there does seem to be a lot of masons in the parade, but who cares?
There's also the fact that whenever we do anything together my husband and I end up watching their kids the whole time- they don't pay a bit of attention. The last time they were here my sil sent the 1.5 yr. old old out to play in the backyard and told the 6 and 7 yr. olds to watch him!
Their kids went into my garage (without permission) and pulled out whatever they wanted (including tools and other things that weren't toys) and left them all over the yard and sidewalk. And their kids are constantly asking to either sleep over at my house or have my kids sleep over at theirs (which will never happen because my brother keeps a loaded gun in the house- great combination with two impulsive kids, huh?).
I just need some sugggestions for how to handle invites without insulting anyone, and without making me feel like it's tons of extra work for my husband and I.
I think telling them you already had plans is fine. You do. You should absolutely not have to ruin your time watching their kids. Maybe you could invite them to do something together over the weekend. All meet together at a park or beach or out somewhere that way they cant rach your house and you'll have to watch the kids.I think the outdoor idea from DianeV is a good one. Someplace where they can blow off a lot of steam like a picnic might make it bearable. Research indicates that exercise helps ADHD kids in particular. It apparently increased the dopamine level and thus aids in self control.
Good luck. We don't choose our relatives.-sometimes the best we can do is to simply survive them.
Diz